Ron Palillo, Horshack of 'Kotter' fame, dies at 63; reactions

That "Ooh! Ooh ooh!" That Horshack laugh. When Ron Palillo died Tuesday morning at his home in Palm Beach Gardens, Fla., another little nugget of '70s pop culture died with him.

Palillo, best known for playing Arnold Horshak in "Welcome Back, Kotter," which ran from 1975 to 1979, died suddenly around 4:30 a.m. EDT, according to the Palm Beach Post, which said he had not been ill. The actor had been teaching acting for film and camera for three years at a charter school for the arts.

"These were 13-, 14-year-old kids [he was teaching], and they didn’t know 'Welcome Back, Kotter,'" Greg Hauptner, founder and CEO of G-Star Academy, told the Post on Tuesday. "The kids went back and watched just about every episode. It drove him crazy, but he loved every minute of it."

Palillo also wrote a play, "The Lost Boy," was artistic director at Palm Beach's Cuillo Center for the Arts, and had numerous theater roles including the off-Broadway production of Lanford Wilson's "Hot L Baltimore," according to Theater Mania.

Palillo's costar Robert Hegyes, who played fellow "Sweathog" Juan Epstein, died this past January at 60 of an apparent heart attack.

"RIP Ron Palillo - Horshack," tweeted Rain Pryor, daughter of Richard Pryor. "I used to impersonate him on stage when my dad or mom performed stand up. I was 5."

A couple of non-celeb types chimed in on Twitter with other examples of what Horshack meant to children of the '70s.

"Sad about Horshack. It explains a lot about me that he was one of my 1st crushes. It explains even more that another one was Soupy Sales," wrote @erdmanmolly.